The European Parliament, made up of European MPs, and EU Council, that comprises member state ministers, would have to approve the waiver for it to enter into practice.

Frans Timmermans, the commission's vice-president, said: "There is still work to be done as a matter of urgency, but if Turkey sustains the progress made, they can meet the remaining benchmarks."

Turkey must fulfil the final five criteria before Turkish citizens can travel visa-free to Schengen area.

The move is part of a package of incentives offered to Turkey — including up to 6bn euros ($6.9bn) in aid for Syrian refugees and fast-track EU membership talks — to persuade Ankara to stop migrants heading to Europe and take thousands back from Greece.

Concerns

The deal has raised legal and moral questions as EU nations, unable to agree among themselves about how to handle the refugee emergency, chose instead to outsource it to Turkey, where almost 3 million refugees are staying, most of them people fleeing war in Syria.

Merkel visits Turkish-Syrian border to bolster refugee deal

Visa liberalisation, which must come by June 30, would be an important sign that the Europeans are living up to their promises.

Turkish President Recep Tayyip Erdogan has warned that the whole agreement will collapse if the EU reneges on any pledge.

Once the visa proposal is endorsed, only Turkish citizens with biometric passports, including facial and fingerprint data, would be allowed to enter, Timmermans said.

Visa-free travel would be possible in all EU member states except for Britain and Ireland, which opted out from Schengen, and would include four non-EU members of the Schengen passport-free travel area, Iceland, Liechtenstein, Norway and Switzerland.